Vehicle with a safety system

ABSTRACT

A safety system for a vehicle is disclosed. The system includes a means for pulling the steering wheel/column away from the driver in the event of a head-on collision, and an inflatable cushion which is mounted on the steering wheel. The pulling away of the steering wheel triggers the inflation of the cushion. Also disclosed is a similar safety system for the passenger side of the vehicle.

FIELD OF THE INVENTION

The invention relates to vehicles equipped with occupant safety systems,particularly automobiles equipped with inflatable air cushions.

BACKGROUND OF THE INVENTION

Automobile accidents kill or injure thousands of people annually. Safetybelts are only effective if worn, and even then may be of limited use incertain types of collisions. Another type of safety system for a vehicledriver provides an inflatable air cushion, or a so-called "airbag", inthe region of the steering wheel. The airbag is connected to apropellant charge, which is detonated via a sensor upon impact. Thecharge fills the bag with air, or other gas, thereby providing a cushionto soften the impending impact. A further air-cushion unit can also beattached to the dashboard for the front-seat passenger.

Currently used airbag systems are not without problems, however. Forexample, the release sensors constitute a safety risk since they canmalfunction, releasing the propellant unexpectedly in non-collisionsituations. In known electrical sensors, there is also the need to checkthe electrical detonation circuits regularly, since faults, such asshort-circuiting, ground contact and cutouts, can lead to the failure ormalfunctioning of the air-cushion unit. Also, electrical connections,for example slip-ring connections to the moveable steering wheel, andthe air-cushion unit mounted in the center of the steering wheel, arerelatively expensive to produce and, in the event of an accident, can bedestroyed even before the sensors are released.

Previously-used release sensors are "acceleration" sensors, which reactto the collision deceleration in an accident. In order to functionreliably, the sensors must be able to distinguish between situations inwhich there should be no release of the air cushion, such as fastoperation decelerations due to hard braking and small minor accidents,and a serious head-on collision, wherein inflation of the air cushionshould occur. The higher the acceleration values required for a releaseoperation, the greater the safeguard against a release malfunction.However, sensors utilizing collision deceleration for release are notalways able to satisfactorily distinguish between decelerations forwhich inflation should occur and those for which it should not.

A frequent effect of a sharp head-on collision is that the vehicledriver strikes the steering wheel with his head, despite having hissafety belt fastened. This is caused by the sharp forward shift of theupper part of the body and the head and/or by the steering wheel beingthrust into the passenger space via the steering column as a result ofthe impact. German Offenlegungsschrift 1,655,597 therefore proposes, inthe event of a head-on collision, to pull the steering wheel away fromthe possible head impact region towards the dashboard by means of acable guided via a deflection device.

In vehicles without a device for pulling away the steering wheel, thesteering column together with the steering wheel can assume an uprightposition in a head-on collision, so that the air cushion is not inflatedtowards the upper part of the body of the vehicle driver, but possiblyonly meets the driver's head. There is therefore the danger of seriousinjury caused by the dipping of the upper part of the body.

SUMMARY OF THE INVENTION

According to the present invention, an inflatable air or gas cushion isprovided in the region of the steering wheel, adjacent a device whichpulls away the steering wheel upon impact, providing a great advantagein that the release mechanism for sensing the need to inflate the aircushion is dependent on the pulling away of the steering wheel, greatlyreducing the chance for inflation malfunction.

The feature that an acceleration sensor as a release mechanism forinflating the air cushion is mounted on the steering wheel or on anupper part of the steering column, which steering wheel and/or columnare pulled away from the driver in the event of a head-on collisionensures that the acceleration sensor experiences a very sharpacceleration for release. The acceleration sensed by the releasemechanism as a result of the pulling away of the steering wheel are ofthe order of several hundred "g's" (acceleration due to gravity), whichis substantially higher than the collision deceleration. The highsteering wheel acceleration is measured and evaluated by theacceleration sensor, so that the release mechanism can be made very safeagainst unintentional releases, because of the high release forceavailable. Furthermore, the release mechanism allows a clear distinctionto be made concerning whether there is only a slight collision, in whichthe inflation of the air cushion is not effected, or a sharp collisionwith a shift of the drive unit relative to the car body under a sharpimpact, with the necessary release of the air cushion.

The release mechanism preferably operates purely mechanically,eliminating the need for electrical connections, which are susceptibleto faults and may be unreliable especially in accidents. Furthermore, itis possible to do without monitoring and checking of such electricaldetonation circuits because of the present invention's independence fromthe vehicle power supply.

Because of the locally confined arrangement of the air-cushion unit andrelease mechanism on the steering wheel, the necessary short releasetimes are guaranteed, even when pyrotechnic lines or direct mechanicalconnections are used between the release mechanism reacting toacceleration and the gas generator of the air-cushion unit.

In one preferred embodiment of the present invention, a sensor mass,which is accelerable in the event of a head-on collision, is positionedbetween a striker, which striker is prestressed by a spring means, and adetonation device for a gas generator of the air-cushion unit. In ahead-on collision, the sensor mass moves away from the region of thestriker, with the result that the striker is released suddenly andstrikes the detonation device because of the spring prestress. Such arelease mechanism can be produced simply and compactly and functionsreliably. Because of the high acceleration forces available, due to thecollapsing or pulled-away steering wheel/column, release of thedetonation device could also occur directly as a result of the movementof the sensor mass, in which case the sensor mass would act as thestriker.

In another preferred embodiment of the invention, a release mechanism ofthe safety system is used for a front-seat passenger. Since no steeringwheel is pulled away on the front-seat passenger side, theabove-described high acceleration values are not available for releasinga further air cushion. In order to ensure a reliable release, whichprevents undesirable releases, for example, in the event of only aslight collision, there is provided a release mechanism which contains asimilar spring-prestressed striker opposite a detonation device.However, in this embodiment of the invention, the striker and thedetonation device are held at a distance from one another by means of abolt, the bolt being connected directly to a cable, which cable isguided via a deflecting unit. In the event of a relatively sharp head-oncollision in which a relative movement takes place between the driveunit and the car body or the fastening point of the deflecting unit, thebolt is released and the detonation device is actuated by the striker.

A release mechanism according to a preferred embodiment of the presentinvention works purely mechanically without electrical connections, thedetonation device containing a detonating cap with a pyrotechnic line tothe gas generator. There is thus no need for a connection to the vehicleelectrical system.

Of course, the above-described release mechanism with the prestressedstriker can also be used when the detonation device contains anelectrical detonation circuit. In this arrangement the striker canactivate the electrical detonation circuit for release reliably inspecific dangerous situations.

According to another preferred embodiment of the invention, it isexpedient to combine the air-cushion unit and the release mechanism intoone unit which can be preassembled and, if appropriate, retrofittedsimply.

Other details, objects and advantages of the invention will becomeapparent as the following description of the presently preferredembodiments and presently preferred methods of practicing the inventionproceeds.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with further features, particulars andadvantages, is explained in more detail by means of the followingdrawings, which are exemplary:

FIG. 1 shows a schematic plan view of the driver's and front-seatpassenger's positions in the region of the dashboard with a preferredembodiment of the invention depicted therein;

FIG. 2 shows a schematic representation of a mechanical releasemechanism of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a safety system 1 with a steering wheel 2, andair-cushion unit 3 in the impact plate of the steering wheel 2, a gasgenerator 4, a release mechanism 5, a steering column jacket 6 connectedto the steering wheel 2, a steering column 7, a grid tube 8, an engineblock 9, a deflecting unit 10 and a cable 11. The safety system 1 isintended for the vehicle driver.

In the event of a head-on collision, the steering wheel 2 is pulledtowards the dashboard 13 in the direction of the arrow 12 out of apossible head impact region of the vehicle driver. For this purpose, thecable 11 is connected at one end to a fastening point 14 on the steeringcolumn jacket 6 and at the other end to a fastening point 15 on theengine block 9. Under a relatively sharp head-on collision, the engineblock 9 is shifted rearwards (upwards in FIG. 1) in the direction of thearrow 16. As a result of the deflecting unit 10, which is secured to astructural part of the vehicle body so as to remain substantially firmlypositioned with respect to the relative rearward movement 16 of theengine block or drive unit 9, this rearward movement of the drive unit 9is transmitted as a pulling movement ot the steering wheel 2 via thecable 11. The deflecting unit 10 is preferably a roller means. Upon thepulling of the steering wheel 2, the grid tube 8 is intentionallycollapsed in the steering column 7, further enabling the steering wheelto be pulled away from the driver. This pulling movement of the steeringwheel, during which an acceleration of several hundred g occurs, is alsoused to release the air-cushion unit 3.

For this purpose, there is provided a release mechanism 5 which is shownin more detail in FIG. 2. A sensor mass 18 is mounted movably in atubular housing 17 and positioned on one side of the housing 17. Thesensor mass 18 preferably takes up less than half the length of thehousing 17 as illustrated. A pointed striker 21 is positioned in atubular piece 19, which piece 19 is perpendicular relative to thehousing 17. The striker 21 is biased against the sensor mass 18 by aspring means 20. Opposite the striker 21, a detonating cap 23 rests in arecess 22 in the housing and is connected to the gas generator 4 via apyrotechnic line 24 (see also FIG. 1). The arrow indicates the directionof travel of the vehicle and consequently the direction of installationof the release mechanism 5.

The safety system 1 functions as follows: in the event of a relativelysharp head-on collision, the engine block 9 or drive unit partsconnected to it are shifted sharply rearwardly in the direction of thearrow 16, with the result that the cable 11 (due to the deflecting unit10) pulls the steering wheel 2 and consequently the release mechanism 5and the housing 17 sharply forwardly (in the direction of travel,indicated by the arrow in FIG. 2 and arrow 12 in FIG. 1) in anaccelerated manner. As a result of the inertia of the sensor mass 18,the relative motion of the sensor mass 18 with respect to the housing 17is such that the sensor mass 18 moves to the left-hand side of thehousing 17, thereby clearing the way for the prestressed striker 21 tostrike the detonating cap 23 in order to release the air-cushion unit 3or the gas generator 4. The cushion unit 26 and release mechanism 5 arepreferably formed as a unit as illustrated.

The front seat passenger safety system 25 of the present invention isalso illustrated in FIG. 1. This system is of simpler design than otherpassenger safety systems, since the air cushion does not come out of anoperationally movable structural part which is accelerated sharplyduring a head-on collision. The safety system 25 of the presentinvention contains an air-cushion unit 26 with a gas generator 27, arelease mechanism 28, a cable 29, a deflecting device 30 and a fasteningpoint 31 for the cable 29. The fastening point 31 is located on theengine block 9 or on a structural part connected to the engine block 9.

The release mechanism for the passenger safety system is also composedof a striker means 33 prestressed by a spring means 32 and a detonatingcap 34 located opposite the striker means 33 and being separatedtherefrom by a bolt means 35. The detonating cap 34 is connected to thegas generator 27 via a pyrotechnic line 36. The cable 29 is fasteneddirectly to the bolt 35 designed as a spacer means.

The safety system 25 functions as follows: in the event of a head-oncollision, the movement of the engine block 9 according to the arrow 16is transmitted directly to the bolt 35 by means of the cable 29 via thedeflecting device 30, which may be a roller means. This cable movementin turn withdraws the bolt 35 and clears the way for the striker 33 tostrike the detonating cap 34, which in turn causes the gas generator 27to be detonated via the pyrotechnic line 36.

The release mechanism 28 is shown diagrammatically and enlarged forillustration and appropriately forms a unit with the air-cushion unit 26or the gas generator 27.

The bolt 35 and the sensor mass 18 can be held securely and without thedanger of premature release malfunctions in a manner known to thoseskilled in the art, for example by means of predetermined breakingconnecting (not shown).

Although the invention has been described in detail in the foregoing forthe purpose of illustration, it is to be understood that such detail issolely for that purpose and that variations can be made therein by thoseskilled in the art without departing from the spirit and scope of theinvention as described by the claims.

I claim:
 1. In an apparatus for enhancing the safety of a person in anautomotive vehicle of the kind comprising a chassis having a portiondeforming in a collision of a predetermined force, drive means mountedfor movement relative to said chassis in response to the deformation,steering means mounted on a column extending in the direction of saidperson, elongate means connected to said chassis and said drive meansfor displacing said steering means in a direction away from said personin response to said movement, first inflatable means for providingprotection between said person and said steering means in suchcollision, the improvement comprising:means for inflating saidinflatable means in response to the displacing of said steering means.2. The apparatus of claim 1, wherein said means for inflating comprisesinertia means moving in response to the displacement of said steeringmeans from a first to a second position.
 3. The apparatus of claim 2,wherein said means for inflating further comprises gas generating meansactuated by an explosive charge, said inertia member when moving to itssecond position releasing firing means of said gas generating means. 4.The apparatus of claim 3, wherein said firing means comprisesspring-loaded striker means separated from an ignition means cap whensaid inertia means is in its first position and movable to strike saiddetonation cap when said inertia means is in its second position.
 5. Theapparatus of claim 4, wherein said inertia means is mounted for movementalong a path intersecting said striker means and said ignition means. 6.The apparatus of claim 5, wherein said inertia means is retained in itsfirst position by frangible means.
 7. The apparatus of claim 4, whereinsaid ignition means comprises detonation cap means.
 8. The apparatus ofclaim 4, wherein said ignition means comprises electrical ignitionmeans.
 9. The apparatus of claim 1, comprising further inflatable meansand said inflating means comprises means responsive to said movement ofsaid drive means.
 10. The apparatus of claim 9, wherein said inflatingmeans comprises latch means operatively connected to said drive means byelongated means for movement from a first to a second position inresponse to said movement of said drive means, said latch means when inits first position retaining spring-biased striker means againstmovement and when in its second position releasing said striker means tomove into engagement with ignition means.
 11. The apparatus of claim 10,wherein said latch means is movable along a path intersecting saidstriker means and said ignition means.
 12. The apparatus of claim 11,wherein said ignition means comprises detonating cap means.
 13. Theapparatus of claim 11, wherein said ignition means comprises electricignition means.